1. Field of the Invention
The invention relates generally to outboard motors and, more particularly, to arrangements for discharging or relieving exhaust gases during idle or low speed operation when the outboard motor is in the normal running position and is either at rest or moving through the water at a low speed.
2. Reference to the Prior Art
When an outboard motor is running at relatively high speeds, exhaust gas is normally discharged underwater through the gear case or through a snout near the bottom end of the drive shaft housing. Such discharge occurs, in part, due to the speed of travel of the outboard motor through the water and, as a consequence, in general, the interior of the exhaust passage in the drive shaft housing is void of water.
When an outboard motor is at rest or when an outboard motor is running through water at slow speeds, water enters into the exhaust gas passage of the drive shaft housing and rises therein to a level approximating the water level outside the drive shaft housing. As a consequence, the exhaust gases are "bottled-up" in the drive shaft housing and an idle exhaust gas relief passage has been provided in the past to afford escape of the exhaust gases at a point in the drive shaft housing located above the normal water level.
Attention is directed to the following U.S. Pat. Nos.:
______________________________________ 3,310,022 Kollman March 21, 1967 3,577,952 Tado May 11, 1971 4,145,988 Harada March 27, 1979 4,303,401 Sanmi, et al. December 1, 1981 4,354,849 Sanmi, et al. October 19, 1982 4,421,490 Nakahama December 20, 1983 4,604,069 Taguchi August 5, 1986 4,607,723 Okazaki August 26, 1986 4,668,199 Freund, et al. May 26, 1987 4,795,383 Binversie, et al. January 3, 1989 4,799,905 Broughton, et al. January 24, 1989 ______________________________________